Overall requirements for the Next Generation (NG) architecture as described in, e.g., Third Generation Partnership Project (3GPP) Technical Report (TR) 23.799 V0.4.0, “Study on Architecture for Next Generation System” and, more specifically, the NG Access Technology as described in, e.g., 3GPP TR 38.913 V0.3.0, “Study on Scenarios and Requirements for Next Generation Access Technologies” will impact the design of the Active Mode Mobility solutions for the New Radio Access Technology (RAT) (NR) as described in, e.g., NTT DOCOMO, “RP-160671: New SID Proposal: Study on New Radio Access Technology,” 3GPP TSG RAN Meeting #71, Mar. 7-10, 2016 compared to the current mobility solution in 3GPP Long Term Evolution (LTE). Some of these requirements are the need to support network energy efficiency mechanisms, future-proofness, and the need to support a very wide range of frequencies, e.g., up to 100 gigahertz (GHz).
One of the main differences, with respect to LTE, comes from the fact that propagation in frequencies above the ones allocated to LTE is more challenging so that the massive usage of beamforming becomes an essential component of NR. Despite the link budget gains provided by beamforming solutions, reliability of a system purely relying on beamforming and operating in higher frequencies might be challenging since the coverage might be more sensitive to both time and space variations. As a consequence, the Signal to Interference plus Noise Ratio (SINR) of that narrow link can drop much quicker than in the case of LTE as described in Ericsson, “R2-162762: Active Mode Mobility in NR: SINR drops in higher frequencies,” 3GPP TSG-RAN WG2 #93bis, Apr. 11-15, 2016.